Conventionally, a configuration in which a rake surface, a step part, and a seating surface are sequentially located inwardly from a corner cutting edge has been proposed as a cutting plate for use in a face milling process (for example, refer to Japanese Unexamined Patent Publication No. 2004-314301).
However, when the cutting plate of Japanese Unexamined Patent Publication No. 2004-314301 is used under conditions that the depth of cut is small, for example, in finish cut, there is a risk that chips extending without being curled and divided may damage a machined surface of a workpiece.
Hence, there is a need for an insert with excellent chip discharge performance in order to suppress quality deterioration of the machined surface of the workpiece due to the chips as described above.